title: Communication: direct angle-resolved measurements of collision dynamics with electronically excited molecules: NO(A2Σ+) + Ar.
abstract: We report direct doubly differential (quantum state and angle-resolved) scattering measurements involving short-lived electronically excited molecules using crossed molecular beams. In our experiment, supersonic beams of nitric oxide and argon atoms collide at 90°. In the crossing region, NO molecules are excited to the A(2)Σ(+)state by a pulsed nanosecond laser, undergo rotationally inelastic collisions with Ar atoms, and are then detected 400 ns later (approximately twice the radiative lifetime of the A(2)Σ(+)state) by 1 + 1(') multiphoton ionization via the E(2)Σ(+) state. The velocity distributions of the scattered molecules are recorded using velocity-mapped ion imaging. The resulting images provide a direct measurement of the state-to-state differential scattering cross sections. These results demonstrate that sufficient scattering events occur during the short lifetimes typical of molecular excited states (∼200 ns, in this case) to allow spectroscopically detected quantum-state-resolved measurements of products of excited-state collisions.
authors.affiliation: Sandia National Laboratories, Livermore, California 94550, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Kay
authors.forename: Grant
authors.initials: G
authors.lastname: Paterson
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Costen
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Strecker
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: McKendrick
authors.forename: David W
authors.initials: DW
authors.lastname: Chandler